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What Really Causes Depression?

Updated on May 27, 2010

What causes depression? I’m not talking about short periods of feeling depressed. We all experience those from time to time. I’m referring to chronic depression, sometimes called clinical depression. This is a long-lasting feeling of sadness, isolation, lethargy, and a loss of interest in friends and activities – all caused by no apparent reason.

In the U.S. alone, almost 18 million people suffer from depression. Approximately 5% of the American population takes prescription antidepressants. Many of those suffering from the condition will be hospitalized, and of that number, 15% will commit suicide.

Depression is a complex issue, and it’s often unique to the individual,. No two cases are exactly the same. Because of this, along with other factors, doctors don’t fully understand the causes of depression. Recent studies, however, have shed some light on the physiological reasons for depression in many individuals.


Serotonin is a neurotransmitter that plays a key role in regulating mood and a sense of well being. Serotonin has a huge impact on the nervous system, controlling things like sleep, appetite, learning, aggression, and memory. When the body does not produce enough serotonin, depression is likely to occur. Many antidepressants treat depression by helping the body with serotonin. The medications do not create more serotonin. Instead, they make more of the serotonin produced be more available to the nerve synapses.

Stress Hormones

The body reacts to stress by releasing certain hormones. Long-term stress and trauma, especially experienced during childhood, can cause permanent negative changes in the nervous system. This trauma might be in the form of physical abuse, mental abuse, verbal abuse, or emotional abuse. One of the culprits, corticotrophin releasing factor, is produced and released in several areas of the brain. Doctors now think that this release prevents the action of the molecules that help alleviate depression. In a nutshell, stress can lead to depression.


When the body is invaded by bacteria and viruses, proteins called cytokines are released. These proteins trigger an inflammatory response, which in turn, can increase the risk for depression. For people already suffering from depression, inflammation can worsen the symptoms, especially the fatigue and disinterest often associated with depression. Chronic illnesses like diabetes, obesity, cancer, cardiovascular disease, and asthma, can also cause inflammation and can thereby increase the chance of developing chronic depression.

Nutritional Deficiencies

People without adequate vitamin B12 in their diets are more prone to depression. Doctors are exactly sure why, but they thing the vitamin helps in the production of monoamines, which help prevent depression. Also, when the body does not get sufficient amounts of B12, amino acids known as homocysteines can build up. These can lead to depression and worsen the symptoms of depression. Natural sources of B12 include meat, eggs, fish, poultry, and dairy products.

Doctors have also discovered that many people with depression have deficient levels of folic acid, or folate. Good sources of this vitamin are mushrooms, bananas, legumes, oatmeal, orange juice, tomato juice, organ meats, broccoli, asparagus, and spinach.

Vitamin B1, also called thiamin, helps the body create energy for the brain. Without sufficient B1, the brain action is suppressed, and depression can occur. Natural source of thiamin include egg yolks, oatmeal, whole grains, brown rice, broccoli, peas, asparagus, milk, legumes, plums, peanuts, fish, poultry, and pork.

Vitamin B6, also known as pyridoxine, is necessary for the production of serotonin and other important neurotransmitters. Without sufficient B6, adequate amounts of serotonin cannot be produced, possibly leading to depression. The best natural sources of vitamin B6 include wheat germ, oat flakes, beef, brown rice, poultry, sardines, cabbage, bananas, and avocado.

Vitamin D also plays a key role in mood and depression. Humans can synthesize this vitamin from sunlight, but with so many people avoiding the sun these days, doctors are concerned that we’re not getting adequate amounts of D. sunscreens block the skin’s vitamin-D producing action, and individuals with darker skin can’t make nearly as much D as can their fair-skin counterparts. A lack of bright light and vitamin D are largely responsible for seasonal affective disorder, also called SAD. Few regularly consumed foods have adequate natural amounts of dietary D. those that do include tuna, salmon, and fish liver oils. Also, some foods are enriched with the vitamin, including milk and other dairy products.

Shrinking Brain Cells

Over a decade ago, scientists discovered that the adult human brain continues to create new brain cells. The hippocampus, part of the brain, goes through periods of making new cells. When it goes too long without creating new cells, this inactivity can lead to depression in some individuals.

Lack of Exercise

Studies suggest that regular, moderate exercise can help prevent depression. An inactive lifestyle can lead to depression. This might be directly related to the explanation of shrinking brain cells, discussed above. Exercise triggers the hippocampus to produce new brain cells, thereby reducing the risk of developing depression.



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    • habee profile image

      Holle Abee 7 years ago from Georgia

      Many thanks for reading, Multiman!

    • profile image

      Multiman 7 years ago

      Great article

    • habee profile image

      Holle Abee 7 years ago from Georgia

      Dave, thanks for reading!

    • dkanofsky profile image

      dkanofsky 7 years ago from Bethalto, Illinois

      Thank you so much for the informative article.

      Kindest regards,


    • habee profile image

      Holle Abee 7 years ago from Georgia

      Thanks, Popeye. It's a terrible condition. I didn't have depression - I had TERRIBLE panic attacks. I'm not sure which is worse!

    • popeye280 profile image

      popeye280 7 years ago from North Yorkshire, England

      Hi Habee great hub with spot on information.

      Having been a sufferer who (eventually) overcame depression I think there are two major insights to highlight for anyone suffering in silence. 1. Prescription drugs do more harm than good, the side effects are worse than the illness! 2.ultimately it has GOT to be you who turns the tide.It may sound impossible but reading hubs, articles and self help material is a fantastic way to drag yourself out of it.Good luck!

    • habee profile image

      Holle Abee 8 years ago from Georgia

      True, Petra. Sad, but true.

    • Petra Vlah profile image

      Petra Vlah 8 years ago from Los Angeles

      Very good information and very good practical advice. Thank you for doing the research and sharing it with us. Depression affects a lot of people and I am afraid that the 5% of them being on anti-depressants is a very low number

      Many people will not admite to taking anti-depressant medication because of the stigma attached to mental illness, which is total ignorance, but is also totally true.

    • habee profile image

      Holle Abee 8 years ago from Georgia

      I'll check it out, Dmitriy!

    • Dmitriy bestlife profile image

      Dmitriy bestlife 8 years ago from Moscow


      The depression is simply a lack of energy. Human organism spends a lot of it in an attempt to fighth the pathogenic factors that surround us everywhere. Instead of dealing with the energy problem and building up the adaptation resources of a human organism, we are prescribed to take chemical drugs.

      I have a realiy unexpected answer to the depression problem. It could be fought in a daytime with the structured water. Take a look at my materials, they are of vital importance. It is not a problem anymore.

    • habee profile image

      Holle Abee 8 years ago from Georgia

      Thanks, Pam! I'm linking your hub to mine.

    • Pamela99 profile image

      Pamela Oglesby 8 years ago from United States

      Habee, This is a very good article as you listed a lot of things that people wouldn't necessarily think of as causing depression. Rated up!

    • habee profile image

      Holle Abee 8 years ago from Georgia

      Thanks, Sheila!

    • sheila b. profile image

      sheila b. 8 years ago

      This was informative. And thanks for your comment about my challah recipe. Once I made this bread, I never made another recipe. It is really that good.

    • habee profile image

      Holle Abee 8 years ago from Georgia

      Thank you, Michelle! I'm glad you found the info helpful, and thanks for reading.

    • Michellcat profile image

      Michellcat 8 years ago

      Great hub, habee! This was well researched, factual, and very helpful.

    • habee profile image

      Holle Abee 8 years ago from Georgia

      Thanks for visiting, Poet!

    • profile image

      poetlorraine 8 years ago

      thanks for writing this it was well researched.

    • habee profile image

      Holle Abee 8 years ago from Georgia

      Hi, Lorlie. About the scores - who knows? I really don't pay a lot of attention to them until one hits 98 or so. And they're never my best hubs. Thanks for visiting!

    • lorlie6 profile image

      Laurel Rogers 8 years ago from Bishop, Ca

      I am at a loss to understand why this beautifully researched hub has such a low score! You have really done your homework, habee, and I am grateful that I found this.

    • habee profile image

      Holle Abee 8 years ago from Georgia

      Thanks, FF. I think a lot of people don't seek help because they think the problem is "all in their head." Maybe if they see that there's an actual physical cause, they'll be more willing to get the help they need.

    • fastfreta profile image

      Alfreta Sailor 8 years ago from Southern California

      You know if people understood some of the facts that you highlighted in your hub as to the reason why they are depressed, maybe they could get help. Your research was topnotch. I'm going to bookmark this hub to send to people that I know that could benefit from it. I truly feel for people that suffer the kind of depression that you spoke of in your hub. Very good hub!

    • habee profile image

      Holle Abee 8 years ago from Georgia

      Why, you are certainly welcome!

    • Waren E profile image

      Waren E 8 years ago from HAS LEFT THE BUILDING............

      Thank you for this informative and well researched hub,habee!


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